With the increasing awareness about personal health, more and more people are looking into readily available nutritious, healthy foods. Yoghurt happens to be one of them and liked by the entire cross section of population irrespective of age and gender of consumers. The consumption of yoghurt has been steadily increasing in the USA as well as worldwide over the years as the life style of working families are changing. Yoghurt prices are also increasing as the cost of processing increases due to the increased cost of energy. Processing of milk to produce yoghurt requires a significant amount of energy and an aseptic processing condition because of direct involvement of live bacterial organisms. Preservation of live bacterial cultures is also an energy intensive process. The conventional yoghurt making process involves use of sugar because the bacterial culture likes to grow in the sugar enriched media present either as dextrose, lactose or sucrose. Artificial sweeteners and nuts can not be used in the conventional process of manufacturing yoghurt using the active culture because the bacteria do not grow well in the presence of artificial sweetener or nuts, especially if lactose-free milk is used. Yoghurt made without any added sugar is very sour.
Often live culture is preferred to supply active cells in the intestine. Stomach bacteria like Lactobacillus and other bacteria are also stabilized and improve their growth rate and number in presence of lactic or gluconic acid. Sometimes healthy presence of bifidobacteria like Lactobacillus and similar species and particularly in the presence of calcium in the same environment reduces chances of getting stomach and/or colon cancer.
The conventional yoghurt manufacturing takes six to twelve hours to produce, because an active culture of Lactobacillus sp. and/or other suitable live culture required fermenting the milk to make the yoghurt. Yoghurt has been produced in the world for centuries, utilizing the active bacterial culture of Lactobacillus sp., Streptococcus sp., and or combination thereof or other active cultures as inoculum. The conventional yoghurt making process involves incubation of active cultures with milk, sugar, and other solidifying agents and chemicals like phosphates, gelatin, starch, etc., and preservatives at 40-45° C. for 6-12 hours. Heating and holding the milk in this temperature range consumes significant quantities of energy. At the end of the incubation period, the coagulated milk takes the form of yoghurt from milk and the product is saved in the refrigerator at or below 4° C. for future processing or consumption.
The conventional yoghurt making process often requires double pasteurization of the product. In the conventional process, the milk is pasteurized first to deactivate and kill the milk borne naturally occurring bacteria. Yoghurt can be further pasteurized after incubation to kill and deactivate the live bacterial culture before serving. After incubation, the milk is converted to yoghurt and then the yoghurt is pasteurized again for deactivating and killing the active cultures prior to storage at 4° C. Repeated pasteurization processes reduce the nutritional value of milk as well as consume significant amounts of energy to heat and cool the yoghurt for short periods of time. Although the pasteurization process does not kill all the bacteria present in the culture, it significantly reduces the live cell number in the yoghurt. After pasteurization some of the residual live bacterial organisms which came from the active cultures stay alive in the yoghurt. These residual organisms reduce the shelf life of yoghurt and also increase the chances of contamination if the container is left open and not consumed completely when it is opened for consumption.
The yoghurt is sold in the supermarkets under refrigerated conditions. Most yoghurt available in the market contain added artificial flavor, fruit, puree, juices and several other chemicals to maintain the consistency of the product. Several additional chemicals are also added to increase the shelf life of yoghurt. Post pasteurized products are also refrigerated to less than 4° C. to enhance the shelf life. Chemicals like sodium phosphate, sorbitol, glycerine and other chemicals are commonly used to make thicker consistency and longer shelf life. Some of these additives may have animal source as origin of the compound like gelatins. Due to the presence of products of animal origin, vegetarians either by religious practice or lifestyle choice do not consume the products.
Maintenance of pure active bacterial culture is an expensive process also and can be a potential source of contamination if not maintained properly. After addition of all the preservatives, the shelf life of conventional yoghurt still suffers because it still contains a small number of bacteria which eventually can spoil the yoghurt over time even if it is stored at a very low temperature. Transportation of yoghurt is always an expensive process for its subnormal storage temperature requirement. The price of yoghurt could be high in the local store due to increased cost of transportation if it is not manufactured locally. Alternately, beneficial bacteria may be added to the yoghurt after the coagulation step. Adding of the bacteria may be accomplished by adding to the top of the yoghurt.
Glucono-delta-lactone, Glucono-gamma-lactone, Calcium Gluconate, Magnesium Gluconate have been used as food additive for a long time as taste enhancers, preservatives and a significant source of mineral supplements. Glucono-delta-lactone also enhances the growth of probiotic bacterial cultures in the intestine.